Suitability evaluation of land reclamation as arable land in coal mining area based on catastrophe theory

Niumasi Coal Mine (located in Shaodong City, Hunan Province, China) was an important producing area of high-quality coking coal in Hunan Province. After large-scale mining of underground coal seams in the area, there has been a large area of surface subsidence and serious land damage. The damaged land urgently needs to be reclaimed. In this paper, the suitability of land reclamation as arable land in Niumasi coal mining area was comprehensively evaluated, and a catastrophe progression model (CPM) for the suitability evaluation of land reclamation as arable land in coal mining area was put forward with the help of the catastrophe theory. The suitability classification was divided into four grades: suitable, moderately suitable, less suitable, and unsuitable. Eleven parameters including terrain slope grade, effective thickness of soil layer, soil parent materials, soil contamination, organic content, alkali hydrolyzable nitrogen (N), available phosphorus (P), available potassium (K), ground collapse, land destruction extent, and conditions of irrigation and drainage were selected as evaluation indicators, and the classification standards of each evaluation indicator was determined. Using MATLAB software to generate a total of 1200 samples (300 samples per level) between the arrays corresponding to each level of standards according to the normal distribution principle, of which 800 samples were used as training samples to establish the catastrophe progression criteria, and 400 samples as test samples to verify the reliability of the proposed criteria. According to CPM, the suitability status of the four land samples in Shuijingtou working area of Niumasi Coal Mine were identified. The evaluation results show that the suitability level of three lands are all 'Moderately suitable', and one sample is 'Unsuitable'. Mining coal has the greatest damage to paddy fields, followed by the dry farming lands and vegetable lands, and the least impact to the forest lands. CPM can not only evaluate the suitability of land reclamation, and comprehensively compare the suitability degrees, but also can assess the damage degree of coal mining to different types of lands. This paper aims to provide a new idea for the study of quantitative evaluation methods of land reclamation suitability. The results have reference and guiding significance for the comprehensive evaluation of the suitability of land reclamation as arable land in coal mining areas.Article highlightsThe catastrophe theory can be used to evaluate the suitability of land reclamation as arable land in coal mining area. A catastrophe progression model for the suitability evaluation of land reclamation as arable land in coal mining area was put forward.Using MATLAB software to establish the catastrophe progression criteria according to the normal distribution principle.The results have reference and guiding significance for the comprehensive evaluation of the suitability of land reclamation as arable land in coal mining areas.